isDefined() (tick_24Global)

int isDefined(string $name)

$name - the name of the variable

Returns 0 if the variable named $name has not been defined, else the function returns nonzero

It is now recommended that isSet() be used instead of this function, if possible (the functionality is slightly different)

Example: to see if $varname is defined, use isDefined('varname'), DO NOT use isDefined($varname)